K, I didn't address the over under pass because of the way I deal with getting the leg pinned. No one every tries that particular option on me, so I didn't think to look at a counter.
I also did mine with the gi, so slight difference there.

OK, so my first escape is very similar to David's except that instead of actively pushing the head I am reaching across to the armpit area and using my body to push the head so that I can get a grip on the gi. I then push out hard with the leg they have pinned and use that to pop my hips out away from the in a very similar manner.
If they have a super good grip on your pants when you do this you will stretch their arm out and then you should attack with an omoplata with the unpinned leg.

The second one is for people who will try to dig in and pass by dropping their head down on the same side as that pinned leg or for when you can shove their head over. I can usually dig up that collar grip without too much trouble, and when I do I prefer to pop out and spin for the loop choke, but the more basic version is to hit the one armed guillotine with the gi grip.